Layered Adhesive Construction With Adhesive Layers Having Different Hydrocolloid Composition

ABSTRACT

A layered adhesive construction comprising a backing layer and a first and second layer of hydrocolloid adhesive, where the first and second layer of hydrocolloid adhesive have different composition, and the second layer of hydrocolloid adhesive is at least partly interposed between the first layer of hydrocolloid adhesive and the backing layer, the first and second adhesive layers consisting of a continuous phase and a discontinuous phase where the discontinuous phase of the first adhesive layer comprises a hydrocolloids providing a higher moisture absorption capacity and higher initial rate of absorption to the adhesive layer than the hydrocolloids in the discontinuous phase of the second adhesive layer, and the discontinuous phase of second layer of adhesive comprises hydrocolloids providing a higher cohesion following moisture absorption to the adhesive compared to the hydrocolloid in the discontinuous phase of the first adhesive layer.

FIELD OF THE INVENTION

The present invention relates to an adhesive construction comprising atleast two layers of hydrocolloid adhesives having a differentcomposition. These adhesive constructions are useful for attachingmedical devices, such as ostomy appliances, to the skin of patients.

In particular the invention relates to an adhesive construction with twoadhesive layers, where the hydrocolloids in the first adhesive layerprovides a higher initial moisture absorption capacity and rate ofmoisture absorption than the hydrocolloids in the second adhesive layer,which second layer on the other hand comprises hydrocolloids providingan improved cohesion following absorption of moisture to the adhesivecompared to the hydrocolloids in the first adhesive layer. The firstadhesive layer with hydrocolloids providing high moisture absorptioncapacity and high rate of absorption is used as skin contact surface,whereas the second adhesive layer with hydrocolloids providing moistureabsorption as well as improved cohesion is at least partly placed awayfrom the skin.

BACKGROUND OF THE INVENTION

Ostomy appliances of the so-called one-piece and two-piece types arecommonly provided with adhesive faceplates for adhesively securing theappliances to the peristomal skin of the wearers, and moisture absorbingskin friendly hydrocolloid containing adhesives have been used asadhesives for these faceplates.

One early type of skin friendly adhesive is disclosed in U.S. Pat. No.3,339,546 and consists of a blend of water-soluble and water swellablehydrocolloids, such as polyvinyl alcohol, pectin, gelatine and/orcarboxymethyl cellulose and a water insoluble elastic binder, such aspolyisobutylene. As the hydrocolloids absorb moisture, such acomposition swells and begins to loose it integrity. In order to resistdissolution/disintegration, new hydrocolloid adhesive formulations weresuggested, which included physically cross-linked elastomers, such asstyrene-olefin-styrene block copolymers and tackifier, see U.S. Pat. No.4,867,748.

U.S. Pat. No. 6,451,883 describes hydrocolloid adhesives comprising apolymer blend consisting of polybutene (in particular polyisobutylene)and a styrene block copolymer (in particular SIS), and a mixture ofhydrocolloids, in particular a mixture of gelatine, pectin andcarboxymethyl cellulose. According to this patent an adhesive may beprepared, which do not contain any tackifier or oil, by selecting anappropriate blend of polybutenes and styrene block copolymers.

The adhesive construction according to the invention comprises at leasttwo layers of hydrocolloid adhesives, one adhesive layer withhydrocolloids providing a high moisture absorption capacity and fastinitial absorption of moisture as the skin contact layer, and a secondadhesive layer with hydrocolloids providing better cohesion than thefirst adhesive layer.

Adhesive constructions comprising layers of hydrocolloid adhesives arewell known in the art:

EP 1 527 789 A1 describes a construction comprising a film layer and atleast two layers of hydrocolloid adhesives with different composition.

The prime object of the adhesive construction described therein is toprovide a multi-layered adhesive medical appliance that has theattributes of a skin friendly wet tack pressure sensitive adhesive foruse adjacent the skin, and a flexible, comfortable, moisture tolerantadhesive that resists degradation after sterilization, and is capable ofcreating a seal around the stoma in a controlled fashion, for use awayfrom the skin.

The adhesive for use adjacent to the skin is described as an adhesivecomprising polyisobutylene and water-soluble or water swellablehydrocolloids.

The adhesive for use away from the skin is described as an adhesivecomprising polyisobutylenes or blends of one or more polyisobutylenesand butyl rubber, one or more styrene radial or block type copolymers,mineral oil, one or more water soluble hydrocolloid gums and atackifier.

It is described that a disadvantage of the known skin-friendly adhesivesused adjacent to the skin is that they tend to be somewhat rigid whenthey become too thick. Thus, it is preferred that the adhesive layeradjacent to the skin is thinner than the more flexible, comfortable,moisture tolerant adhesive, which is used away from the skin.

The layered adhesive construction according to the invention differ fromthe construction described in EP 1 527 789 A1 in that the characteristicof the hydrocolloids are different in the two layers and in that thecontinuous phase (see below) is identical or essentially identical inthe two layers.

EP 686 381 B2 describes similar adhesive constructions with two layersof hydrocolloid adhesives with different composition. According to thispatent, the layer of adhesive securing the adhesive construction to theskin is composed of a skin friendly hydrocolloid containing adhesivethat has a relatively low resistance to dissolution and/ordisintegration when contacted by stomal fluids, whereas the otheradhesive layer placed away from the skin is composed of a relativelysoft, easy-deformable and extrudable, adhesive sealant material that ismore resistant to dissolution or disintegration by stomal fluids thanthe material of the skin contact adhesive. From the drawings it is clearthat the adhesive layer adjacent to the skin is thinner than theadhesive layer placed away from the skin.

Again the layered adhesive construction according to the inventiondiffers from the construction described in EP 686 381 in that thecharacteristics of the hydrocolloids are different in the two layers andin that the continuous phase is identical or essentially identical inthe two layers of adhesive.

EP 413 250 A1 describes an adhesive construction for use e.g. as part ofan ostomy device, which comprises a backing layer and two layers ofhydrocolloid adhesive. According to this document, both adhesive layersare in contact with the skin, the adhesive layer contacting the skin inthe central part of the device being more than twice as thick as theadhesive layer contacting the skin in the peripheral portion of theconstruction.

It is indicated that the continuous phase of the two adhesive layers maybe the same or may be different. Two different compositions, where thepolymeric or continuous phase is different and the blend ofhydrocolloids is identical, but present in different amounts, arementioned for the adhesive layers.

U.S. Pat. No. 4,538,603 also describes an adhesive constructioncomprising two adhesive layers, which are of different composition, andwhere the adhesive layer intended for skin contact is thicker than theadhesive layer placed away from the skin. The adhesive layer placed awayfrom the skin is relatively thin and bonded to a foam layer carrying afilm on the surface facing away from the adhesive layer. The adhesiveconstruction described herein is constructed be useful for coveringexudating wounds or ulcers. It is described that the relatively thickskin contact layer, is composed of ingredients permitting the adhesiveconstruction to remain in place on the skin for several days. The waterdispersible hydrocolloids, the water swellable cohesive strengtheningagents and the hydratable polymers distributed throughout the adhesivelayer gradually becomes hydrated over time. Eventually the adhesivelayer becomes so hydrated that the construction can be removed withoutstripping or macerating the skin around the wound site. The relativelythick adhesive layer to be placed on the skin comprises thermoplasticelastomer, such as low molecular weight polyisobutylene, andhydrocolloids, water swellable cohesive strengthening agents andhydratable polymers, whereas the relatively thin adhesive layer placedaway from the skin and bonded to the foam layer may also compriseplastizisers and tackifiers.

Again, the two layers of hydrocolloid adhesives have differentcontinuous phase.

WO 94/15562 describes adhesive constructions consisting of twoadhesives, where one adhesive constitutes a layer in the form of anisland embedded into the other adhesive layer. It is described how theadditional material unit which makes up the island may be of a lesscohesive material than the adhesive material making up the rest of theconstruction.

It is also described how the difference in cohesiveness in the twoadhesives used is achieved by using a different continuous phases forthe two adhesives, while the mixture of hydrocolloids remains the samein the two layers.

The layered adhesive construction according to the invention differ fromthe known layered adhesive constructions in that the discontinuous phase(or the hydrocolloids) is different in the two layers, in that thecontinuous phase of the adhesive is identical or essentially identicalfor the two layers of hydrocolloid adhesive and/or in that the skincontact adhesive layer is thinner than the adhesive layer interposedbetween the backing layer and the skin contact adhesive layer.

The adhesive construction according to the invention comprises at leasttwo adhesive layers, one first adhesive layer with hydrocolloidsproviding a high initial moisture absorption capacity and fastabsorption of moisture to the adhesive as the skin contact layer, and asecond adhesive layer comprising hydrocolloids providing a good moistureabsorption capacity and improved cohesion following absorption comparedto the first adhesive layer. The second adhesive layer is at leastpartly placed behind the first adhesive layer and away from the skin,and is preferably thicker than the first adhesive layer. The thickersecond layer of adhesive provides together with its absorption capacity,an effective transportation of moisture from the first adhesive layerand into the second adhesive layer, whereby disintegration and formationof pools of disintegrated adhesive between the skin and the firstadhesive layer is diminished.

Due to the absorption capacity of the second adhesive layer, it willswell once it begins to absorb moisture from the first adhesive layer orpossibly other sources. This is a particular advantage when the adhesiveconstruction of the invention has a hole for receiving a stoma and isused as a faceplate for an ostomy appliance, because the second adhesivelayer may swell and act to provide a seal in a situation where the firstadhesive layer has become partly disintegrated in an area around thestoma.

By selecting the same continuous phase for the two adhesive layers, thelayers become fully compatible with each other and migration ofcomponents from one layer into the other is avoided.

SUMMARY OF THE INVENTION

Thus, the present invention relates to a layered adhesive constructioncomprising a backing layer and a first and second layer of ahydrocolloid adhesive, where the first and second layer of hydrocolloidadhesive have different composition, and the second layer ofhydrocolloid adhesive is at least partly interposed between the firstlayer of hydrocolloid adhesive and the backing layer, the first andsecond adhesive layers consisting of a continuous phase and adiscontinuous phase, where

a) the discontinuous phase of the first adhesive layer compriseshydrocolloids providing a higher moisture absorption capacity and higherinitial rate of moisture absorption to the adhesive than thehydrocolloids in the discontinuous phase of the second adhesive layer,andb) the discontinuous phase of the second adhesive layer compriseshydrocolloids providing a higher cohesion following moisture absorptionthan the hydrocolloids in the discontinuous phase of the first adhesivelayer.

DETAILED DESCRIPTION OF THE INVENTION

As used herein “discontinuous phase” means the hydrocolloid(s) ormixture of hydrocolloids and any other particulate solids in theadhesive layers, such as filler (native starch), colours etc.

As used herein “continuous phase” means the total adhesive compositionexcept the discontinuous phase as defined above.

As used herein “a higher cohesion following moisture absorption” inrelation to two hydrocolloid adhesives, means a lower degree ofdisintegration/dissolution of the adhesive when the adhesives areexposed to water under the same conditions.

The difference in cohesion of adhesives may be evaluated by coveringdimensionally identical samples of adhesives with saline (0.9%) at atemperature of 37° C. for a period of time (suitable 18 hours) and thenevaluating the cohesiveness visually and by touching and manipulatingthe samples to evaluate whether and to what degree disintegration ordissolution has taken place.

The “absorption capacity” is the amount of water absorbed when theadhesive has been saturated with water. The absorption capacity may bemeasured by mounting dimensionally identical samples (e.g. a 25×25 mmsample which is 1 mm thick) on a glass plate and covering the sampleswith saline (0.9%) at 37° C.±2° C. and weighing the sample (after liquidon the surface of the sample has been wiped off) after 5 min, 10 min, 20min 30 min, 60 min and 120 min, or until there is no further increase inweight and then calculating the absorption capacity as the weight ofwater absorbed per weight unit of adhesive, or per area unit ofadhesive, when the adhesive is saturated with water.

As used herein “initial rate of absorption” is the rate of absorption at5 minutes. The initial rate of absorption may be measured by mountingdimensionally identical samples (e.g. a 25×25 mm sample which is 1 mmthick) on a glass plate and covering the samples with saline (0.9%) at37° C.±2° C. for 5 minutes and weighing the sample after liquid on thesurface of the sample has been wiped off, and then calculating theincrease in weight per weight unit adhesive or per area unit of adhesiveand calculating the rate of absorption in the first 5 minutes bydividing with 5.

As used herein a “faceplate for an ostomy appliance” means a planaradhesive construction useful for attaching a bag to the peristomal skinof a patient and for protecting the skin surrounding the stoma.

The hydrocolloids in the adhesive layers may be on single type ofhydrocolloid or a mixture of hydrocolloids.

Suitably, the hydrocolloids (or the mixture of hydrocolloids) in thefirst and second layer of the adhesives are different.

The continuous phases of the first and of the second adhesive layers aresuitable identical or essentially identical.

As used herein “essentially identical” means that other components canbe present in minor amounts in one continuous phase compared to theother continuous phase (less than 0.5% deviation pr component from onecontinuous phase to the other) and/or there is a minor deviation in thecomposition of the two continuous phases, such that each constituent ofone phase is present ±0.5% in the other phase.

According to a preferred embodiment of the invention, the first layer ofhydrocolloid adhesive comprises hydrocolloids, which are capable ofabsorbing a high amount of moisture at a high initial rate ofabsorption, i.e. a hydrocolloid such as carboxymethylcellulose (inparticular sodium carboxymethyl cellulose) or another hydrocolloidproviding similar absorption capacity and high initial rate ofabsorption to the adhesive. A disadvantage of such an adhesivecomposition is that the adhesive has a tendency to disintegratefollowing absorption of moisture, in particular if the moisture is noteffectively transported through and away from the adhesive layer.

The second layer of the adhesive construction of the invention comprisesa hydrocolloid providing a high cohesion to the adhesive followingabsorption of moisture, such as guar gum or other hydrocolloidsproviding similar good absorption and cohesion following absorption tothe adhesive. Preferably, the second layer of adhesive is thicker thanthe first layer whereby the absorption capacity of the adhesive layer assuch increases.

The combination of the two layers where the first adhesive layer, whichis in contact with the moisture on the skin, has a high and fast initialmoisture absorption with a layer of hydrocolloid adhesive which iscapable of absorbing large amounts of moisture while preserving itsintegrity (high cohesion), provides an adhesive construct where moistureis effectively taken up by the first adhesive layer and transportedthought the first layer of adhesive and into the second layer ofadhesive. This means that the wet tack of the first adhesive layer ispreserved and the disintegration thereof diminished.

The first adhesive layer need not be particularly thick and ispreferably thinner than the second adhesive layer.

The hydrocolloids used in the layers of the adhesive construction of theinvention may be selected from natural, synthetic and semi-synthetichydrocolloids. Hydrocolloids useful in adhesives are well known in theart. Suitable water soluble and water swellable hydrocollids includescarboxymethyl cellulose (e.g. sodium carboxymetyl cellulose), pectin,gelatine, guar gum, locust bean gum, gum karaya, etc.

According to one embodiment of the invention, the discontinuous phase ofthe first adhesive layer comprises 40-50% w/w, preferably 45% w/w (basedon the weight of the discontinuous phase) of sodiumcarboxymethylcellulose or a hydrocolloid providing similar absorptioncapacity and initial rate of absorption to the adhesive, and thediscontinuous phase in the second adhesive layer comprises 35-45% w/w,preferably 40% w/w (based on the weight of the discontinuous phase), ofguar gum or a hydrocolloid providing similar absorption capacity andcohesion following moisture absorption to the adhesive.

Preferably, the discontinuous phase of the first adhesive layercomprises between 40 and 50% w/w, preferably 45% w/w of carboxymethylcellulose (suitably sodium carboxymethyl cellulose) and thediscontinuous phase of the second adhesive layer comprises between 35and 45% w/w, preferably 40% w/w of guar gum and 15-25% w/w, preferably20% w/w carboxymethyl cellulose (e.g. sodium carboxymethyl cellulose).

The hydrocolloids in the first adhesive layer in any of the embodimentsabove, is suitably a mixture of pectin, gelatine andcarboxymethylcellulose (suitably sodium carboxymethyl cellulose) and thehydrocolloids in the second adhesive layer is suitably a mixture of guargum, gelatine and carboxymethylcellulose (e.g sodium carboxymethylcellulose).

The hydrocolloids in the discontinuous phase of first adhesive layer,suitably comprises a mixture of:

40-50% w/w, preferably 45% w/w of carboxymethyl cellulose (e.g sodiumcarboxymethyl cellulose)15-25% w/w, preferably 20% w/w pectin, and30-40% w/w, preferably 33-35 5 w/w gelatine based on the weight of thediscontinuous phase.

The hydrocolloids in the discontinuous phase of the second adhesivelayer, suitably comprises a mixture of:

35-45% w/w, preferably 40% w/w of guar gum,15-25% w/w, preferably 20 w/w carboxymethyl cellulose (e.g sodiumcarboxymethyl cellulose), and35-45% w/w, preferably 40% w/w gelatine based on the weight of thediscontinuous phase.

The, first adhesive layer suitably comprises 45-55% by weight of thediscontinuous phase, preferably 50% of the discontinuous phase.

The second adhesive layer also suitably comprises 45-55% by weight ofthe discontinuous phase, preferably 50% of the discontinuous phase.

The composition of the polymer matrix of the first and second adhesivelayer is preferably identical or essentially identical.

The continuous phase of the two adhesive layers may be any known polymercomposition providing a pressure sensitive adhesive suitable forattachment to the skin.

Preferably, the continuous phase consist of a mixture of a styrene blockcopolymer with a liquid viscous polyolefin, such as polyisobutylene. Theneed for oil to soften the styrene blocks and the tackifier to improvethe adhesive properties of the continuous phase, may be avoided byselecting the appropriate blend of styrene block copolymer in relationto the amount of liquid viscous polymer, see U.S. Pat. No. 6,451,883.

According to another embodiment of the invention, the continuous phasementioned above may contain up to 15% w/w of tackifier resin, oil etc.

According to a preferred embodiment of the invention, the continuousphase comprises 15-25% w/w, preferably about 20% w/w styrene blockcopolymer, such as Kraton D1107, Kraton D-1161 NU or similar styreneblock copolymers and 75-85% w/w, preferably 80 w/w liquid viscouspolyisobutylene, such as Oppanol B 12 SFN.

Such compositions are described in U.S. Pat. No. 6,541,883.

In one embodiment of the invention the second adhesive layer isextending beyond the peripheral edge of the first adhesive layer, andmay contact the skin beyond the area where the first adhesive layercontacts the skin. According to this embodiment of the invention, thefirst adhesive layer may be thinner than the second adhesive layer andthe first adhesive layer may be embedded in the second adhesive layer.This embodiment of the invention is illustrated in FIG. 1 showing thebacking layer (1), the second adhesive layer (2) and the first adhesivelayer (3).

As used herein “embedded” means that one layer is embedded in the otherlayer in such a way that only one of the surfaces of embedded layer isnot covered by the other layer. These adhesive constructions may beprepared as described in WO 00/18554.

In another embodiment of the invention the second adhesive layer isattached on top of the first adhesive layer and the second adhesivelayer is extending beyond the peripheral edge of the first adhesivelayer, and may contact the skin beyond the area where the first adhesivelayer contacts the skin. This is illustrated in FIG. 2 showing thebacking layer (1), the second adhesive layer (2) and the first adhesivelayer (3). Suitably, the first adhesive layer is thinner than the secondadhesive layer.

The first and second adhesive layer may have the same area and shape andbe aligned on top of each other. Again, the first adhesive layer ispreferably thinner than the second adhesive layer see FIG. 3 showing thebacking layer (1), the second adhesive layer (2) and the first adhesivelayer (3). These adhesive constructions are prepared by preparing thelayers separately and laminating the second adhesive layer between thebacking layer and the first adhesive layer.

Suitably, the thickness of the first adhesive layer is suitably 0.1-0.4mm, preferably 0.25-0.35 mm, or more preferred 0.3 mm and the thicknessof the second adhesive layer interposed between the backing layer andthe first adhesive layer is suitably between 0.5-1 mm, preferably0.5-0.9 mm, more preferred 0.5-0.8 mm, or more preferred 0.5-0.7 mm.

The adhesive construction according to the invention may have bevelledperipheral edges where both adhesive layers are bevelled, or in case thesecond adhesive layer is extending beyond the peripheral edges of thefirst adhesive layer, only the second adhesive layer is bevelled. Thisis illustrated in FIG. 1. As indicated the second adhesive layer maybecome thinner than the first adhesive layer in the bevelled peripheralportion.

The surface of the adhesive layer (e.g. the second adhesive layer)attached to the backing layer is suitably covered completely by thebacking layer.

The backing layer may be a thin polymeric film, film having multiplepolymeric layers, a non-woven fabric, or an open celled or closed celledfoam layer optionally having its outer surface covered by a film.

Suitable material for thin polymeric films include polyolefins, such aspolyethylene, polypropylene, ethylene acrylic acids, ethylene vinylacetates, polyvinylchlorides, polyether sulfones, polyether ketones,polyurethanes etc. The polymeric films are suitably impermeable toliquid water and may have a varying degree of water vapour permeability.Suitable non-woven fabrics include those made from polyester fibres,polypropylene fibres, nylon fibres, composite olefin fibres, orcellulose

The thickness of the backing layer may vary depending on the material itis made of. The thickness of the backing layer is suitably 30-100 μm,preferably 40-70 μm.

The backing layer may also be a foam layer as described in U.S. Pat. No.4,538,603. The backing layer may be of a weldable material so that otheritems or devices may be welded onto the backing layer.

Release liners the types well known in the art may be applied to theadhesive surface of the adhesive construction according to theinvention. Such release liners are well known in the art.

The adhesive construction according to the invention may containadditional adhesive layers, additional film layers or other layers.

According to a further embodiment of the invention, the layered adhesiveconstruction has a pattern of indentations in the form of groves in thesurface provided with the backing layer.

These groves improve the flexibility of the adhesive construction andare formed in the adhesive layer(s) nearest to the backing layer (e.gthe second adhesive layer), leaving the backing layer and the skincontact adhesive layer intact. The depth of the groves is preferablysmaller than the thickness of the adhesive layer(s) nearest the backinglayer, e.g. the second adhesive layer.

According to one embodiment, the indentations are extending radicallyfrom the center of the layered adhesive construct towards the peripheryof the layered adhesive construct. Optionally the adhesive constructalso has curvilinear indentations, which are crossing the radialindentations.

The use of indentations to improve the flexibility of an adhesiveconstruct has been described in WO 04/087004.

EXPERIMENTALS Materials

Oppanol B 12 SFN, a polyisobutylene from BASF, MW: 60.000-80.000Kraton D-1161 NU, a SIS block copolymer from KRATON PolymersAkucell AF 2881, sodium carboxymethyl cellulose from AKZOGelatine UF 220 from PB GelatinsGuar Gum FG-200 from Nordisk GelatinePectin Pomosin LM 12 CG-Z/200 from Copenhagen PectinBayferrox, Fe₂O₃ obtainable from Bayer.

Example 1

Composition of second adhesive layer:

Ingredient Amount in gram Oppanol B 12 SFN 40 Kraton D-1161 NU 10Akucell AF 2881 10 Gelatine UF 220 20 Guar Gum FG-200 20

Example 2

Composition of first adhesive layer:

Ingredient Amount in gram Oppanol B 12 SFN 40 Kraton D-1161 NU 10 PectinPomosin LM 12 CG-Z/200 10 Akucell AF 2881 22.5 Gelatine PB 220 17.47Bayferrox 0.03

Example 3

The hydrocolloid adhesives may be prepared by heating the ingredients ina Z-mixer according to methods well known in the art and the layeredadhesive construction may be prepared according to the method describedin WO 00/18545.

Four clinical studies were performed using the layered adhesiveconstruction.

Example 4

In study DK 151 OS (Approved by Freiburger ethic-kommision, Study Code:DK145OS, Feci Code: 05/1609) 64 German individuals with an ileostomytested the layered adhesive construction with a drainable bag comparingit to a reference product, Moderma Flex “air space technology” singlelayer adhesive from Hollister inc. The study was an open, randomised,comparative, crossover multi-centre study. The study showed thatparticipants experienced less erosion with the layered adhesive, 77%experienced a little or no erosion with the layered adhesive and 55% forthe reference. Also immediate adhesion to the skin (tack) was deemedsignificantly better with the layered adhesive experienced by 83%,whereas it was 55% for the reference, as well as less pain when removingthe layered adhesive compared to the reference.

Example 5

In the Feasibility study DK 153 OS (Approved by Comite Consulatatif deProtection des Personnes dans la Recherché Biomedicale de hauteNormandie Aug. 12, 2005 sous le no 2005/031) 59 French individuals withan ileostomy tested the layered adhesive construction with a drainablebag comparing it to a reference product, Esteem with Invisiclose fromConvatec. The study was an open, randomised, comparative cross-overstudy. The study showed that the immediate adhesion to the skin (tack)was found to be “good” or “very good” with the layered adhesive by 93%of participants compared to 66% for the Esteem adhesive. Adhesion duringuse was also experienced to be “good” or “very good” by 76% with thelayered adhesive, which was significantly better than the 45%experienced for the Esteem adhesive. Immediate adhesion and adhesionduring use are linked to initial rate of water absorption and waterabsorption after 120 minutes. The study also showed that participantsexperienced significantly less adhesive residues left on the skin whenusing the layered adhesive. Also a significantly better feeling ofsecurity was experienced with the layered adhesive construction.

Example 6

In the Feasibility study DK 109 OS (Approved by RegionaleVidenskabsetiske Komité ØST J.nr.: 2005-2-07G) 68 Danish individualswith a colostomy tested the layered adhesive construction with a closedbag. The product was tested against the comparator, Nova 1, with asingle layer adhesive from Dansac NS. The study was a randomized,comparative crossover-study. The study showed that the immediateadhesion to the skin (tack) and adhesion during use was significantlybetter when using the layered adhesive construction compared to thereference product (Immediate adhesion p<0.0001 and Adhesion during usep<0.0175). Immediate adhesion and adhesion during use are linked toinitial rate of water absorption and water absorption after 120 minutes.Pain when removing the bag was also found to be significantly lesscompared to the reference product as well at the general feeling ofsecurity.

Example 7

In Feasibility study DK 145 OS (Approved by Freiburger ethic-commission,Study Code: DK145OS, Feci Code: 05/2099) 69 German individuals with acolostomy tested the layered adhesive construction with a closed bag.The product was tested against the comparator, Moderma Flex fromHollister. The study was a randomised comparative, crossover-study. Thestudy showed that the immediate adhesion to the skin (tack) wassignificantly better when using the layered adhesive constructioncompared to the reference product (p<0.0001).

As mentioned earlier, the first adhesive layer with hydrocolloidsproviding high moisture absorption capacity and high rate of absorptionis used as skin contact surface, whereas the second adhesive layer withhydrocolloids providing moisture absorption as well as improved cohesionis at least partly placed away from the skin. That cohesion is strongerfor the layered adhesive after being covered with water with 0.9% NaClfor 18 hours is shown in Test report from the Danish Technologicalinstitute journalnr. 1220519-02 fgu/eta. This is shown for each ofConvatec, Dansac A/S and Hollister adhesives.

1. A layered adhesive construction comprising a backing layer and afirst and second layer of hydrocolloid adhesive, where the first andsecond layer of hydrocolloid adhesive have different composition, andthe second layer of hydrocolloid adhesive is at least partly interposedbetween the first layer of hydrocolloid adhesive and the backing layer,the first and second adhesive layers consisting of a continuous phaseand a discontinuous phase wherein a) the discontinuous phase of thefirst adhesive layer comprises a hydrocolloids providing a highermoisture absorption capacity and higher initial rate of absorption tothe adhesive layer than the hydrocolloids in the discontinuous phase ofthe second adhesive layer, and b) the discontinuous phase of secondlayer of adhesive comprises hydrocolloids providing a higher cohesionfollowing moisture absorption to the adhesive compared to thehydrocolloid in the discontinuous phase of the first adhesive layer. 2.The layered construction according to claim 1 wherein the hydrocolloidsor mixture of hydrocolloids in the discontinuous phase of the first andthe second adhesive layer are different.
 3. The layered constructionaccording to claim 1 wherein the composition of the continuous phase ofthe first and of the second adhesive layer are identical or essentiallyidentical.
 4. The layered adhesive construction according to claim 1wherein the discontinuous phase of the first adhesive layer comprises40-50% w/w of carboxymethylcellulose or a hydrocolloid providing similarmoisture absorption capacity and initial rate of absorption to theadhesive, and the discontinuous phase of the second adhesive layercomprises 35-45% w/w guar gum or a hydrocolloid providing similarcohesion to the adhesive.
 5. The layered construction according to claim4 wherein the discontinuous phase of the first adhesive layer comprisesbetween 40 and 50% w/w, preferably 45% w/w of carboxymethyl cellulose.6. The layered adhesive construction according to claim 4 wherein thediscontinuous phase of the second adhesive layer comprises between 35and 45% w/w, preferably 40% w/w of guar gum, and 15-25% w/w, preferably20% w/w carboxymethyl cellulose
 7. The layered construction according toclaim 1 where the discontinuous phase in the first adhesive layercomprises pectin, gelatine and sodium carboxymethyl-cellulose and thediscontinuous phase in the second adhesive layer comprises guar gum,gelatine and sodium carboxymethyl cellulose.
 8. The layered adhesiveconstruction according to claim 7 where the first adhesive layercomprises a mixture of: 40-50% w/w, preferably 45% w/w of carboxymethylcellulose, 15-25% w/w, preferably 20% w/w pectin, and 30-40% w/w,preferably 33-35% w/w gelatine based on the weight of the discontinuousphase, and the second adhesive layer comprises a mixture of: 35-45% w/w,preferably 40% w/w of guar gum, 15-25% w/w, preferably 20% w/wcarboxymethyl cellulose and 35-45% w/w, preferably 40% w/w gelatinebased on the weight of the discontinuous phase.
 9. The layeredconstruction according to claim 1 wherein the first adhesive layercomprises 45-55% by weight of the discontinuous phase, preferably 50% ofthe discontinuous phase.
 10. The layered construction according to claim1 wherein the second adhesive layer comprises 45-55% by weight of thediscontinuous phase, preferably 50% of the discontinuous phase.
 11. Thelayered construction according to claim 1 wherein the first adhesivelayer is thinner than the second adhesive layer at least in the areawhere the second adhesive layer is interposed between the backing layerand the first adhesive layer.
 12. The layered construction according toclaim 11 wherein the second adhesive layer is extending beyond theperipheral edge of the first adhesive layer.
 13. The layered adhesiveconstruction according to claim 12 wherein the first adhesive is thinnerthan the second adhesive layer and is embedded in the second adhesivelayer.
 14. The layered adhesive construction according to claim 12wherein the second adhesive layer is placed on top of the first adhesivelayer.
 15. The layered construction according to claim 11 wherein thefirst and second adhesive layer have the same area and shape and arealigned on top of each other.
 16. An ostomy appliance comprising anadhesive construction according to claim 1.